Want to be able to display the source code of any webpage, with line numbering? Here is a simple code snippet to do it. Just modify the url on line 2 at your convenience. Or even better, make a pretty function according to your needs.

// display source code
$lines = file('http://google.com/');
foreach ($lines as $line_num => $line) { 
	// loop thru each line and prepend line numbers
	echo "Line #<b>{$line_num}</b> : " . htmlspecialchars($line) . "<br>\n";
}